1. Field of the Invention
The present invention relates to an endoscope in which an operation wire is pulled by a curving operation in a curving operation portion provided in an operation portion to curve a curving portion.
2. Description of the Related Art
In general, a medical endoscope includes a curving portion provided in a part of the distal direction side of an insertion portion to be inserted into a body cavity. In an operation portion which is provided in a proximal direction side to the insertion portion, a curving operation portion such as a curving operation knob or a curving operation lever which performs a curving operation of the curving portion is provided rotatably around a pivot shaft. An operation wire for the curving operation is provided within the insertion portion and within the operation portion. The operation wire is pulled by the curving operation in the curving operation portion to curve the curving portion.
For example, Jpn. Pat. Appln. KOKAI Publication No. 2000-126119 shows an endoscope including a two-way curving mechanism in which a curving portion is curved in a first curving direction and in a second curving direction opposite to the first curving direction. In this endoscope, the curving portion is curved in the first curving direction or the second curving direction by rotating a curving operation lever as a curving operation portion. The curving operation lever is capable of rotating in a first rotation direction and in a second rotation direction opposite to the first rotation direction. The relationship between the rotation direction of the curving operation lever and the curving direction of the curving portion is set, for example, as follows: The curving portion is curved in the first curving direction by rotating the curving operation lever in the first rotation direction. The curving portion is curved in the second curving direction by rotating the curving operation lever in the second rotation direction. The condition in which the curving operation is performed as mentioned above is referred to as a first set condition.
On the other hand, the relationship between the rotation direction of the curving operation lever and the curving direction of the curving portion varies depending on user preference. It is therefore desired to provide an endoscope in which the relationship between the rotation direction of the curving operation lever and the curving direction of the curving portion is adaptable to the user preference. For example, the following types of endoscopes including the two-way curving mechanisms are used; a type that performs the curving operation in the first set condition; and a type that performs the curving operation in a second set condition in which the relationship between the rotation direction of the curving operation lever and the curving direction of the curving portion is opposite to that of the first set condition. In the second set condition, the curving portion is curved in the second curving direction by rotating the curving operation lever in the first rotation direction. The curving portion is curved in the first curving direction by rotating the curving operation lever in the second rotation direction. A user selectively uses one of the types in the first set condition and the second set condition suitably to his/her preference.
Moreover, an endoscope provided with a wire crossing portion in which two operation wires cross each other in an operation portion is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2005-65931. The wire crossing portion is provided so that the relationship between the rotation direction of the curving operation lever and the curving direction of the curving portion is opposite to that in the case where no wire crossing portion is provided.